The 38kg heavy rail is a rail section with a nominal weight of about 38 kg per meter, commonly supplied in U71Mn manganese steel. It is used in railway construction, especially where high strength and high wear resistance are required but full-size heavy rails would be over-specified. This article explains its material, mechanical behavior and practical application considerations.
What Is a 38kg Rail
The 38kg rail belongs to the heavy rail family defined in Chinese national standard practice, with a rail height of about 134 mm, head width of 68 mm, bottom width of 114 mm and web thickness of 13 mm. Its actual mass is about 38.7 kg/m. It is lighter than standard 50 kg/m or 60 kg/m main-line rails and is typically chosen for secondary lines, mine railways, industrial tracks and other medium-load applications.
Material and Composition
The 38kg rail is mainly made of U71Mn manganese steel, where the addition of manganese significantly improves hardenability, tensile strength and wear resistance. This grade combines high load capacity with good ductility, making it suitable for tracks that experience frequent shunting, heavy wagons and abrasive traffic.
When supplied in U71Mn per GB/T 2585-2007, the rail offers guaranteed mechanical properties verified by batch testing. Typical guaranteed values are a tensile strength of at least 880 MPa and elongation of at least 9%, with the surface hardness controlled so the rail resists indentation and wear. Lower-strength grades are possible for lighter duties, and the applicable grade should always be confirmed against the project specification.
| Property | Guaranteed Value (U71Mn) |
|---|---|
| Tensile strength | ≥ 880 MPa |
| Elongation | ≥ 9% |
| Wear resistance | High, via manganese alloying and heat treatment |
Corrosion Resistance
The manganese-bearing composition improves the corrosion behavior of the steel, especially in wet or chemically aggressive environments, extending service life compared with plain carbon sections. Surface protection during storage remains important before installation.
Application Scenarios
The 38kg rail is mainly used for track laying in mine railways, industrial sidings, ports and large industrial plants where heavy loads must be carried without the cost of 60 kg/m sections. It is also used on secondary and branch lines of national networks. It is not intended for high-speed passenger corridors, which require heavier sections with stricter profile and surface quality.
Installation and Maintenance
Compared with 60 kg/m rails, 38kg rails are easier to handle, install and replace, reducing construction difficulty and cost. Their good wear resistance and corrosion resistance reduce later maintenance work. Fasteners, fish plates and sleepers must be matched to the 38kg profile, and joints should be checked regularly for bolt torque and alignment.
Common Misconceptions
One misconception is that the 38kg rail is a substitute for 60 kg/m rails on main lines; its section modulus is lower and it is designed for medium loads. Another is that heavier rails are always more economical; the right section matches axle load and traffic density to avoid both under-specification and wasted cost.
FAQ
Q: What is a 38kg heavy rail? A: A rail section of about 38 kg/m, commonly supplied in U71Mn steel for medium-load industrial and secondary lines.
Q: What material is the 38kg rail made of? A: Usually U71Mn manganese steel, which improves hardenability, strength and wear resistance.
Q: What is the tensile strength of a U71Mn rail? A: At least 880 MPa with elongation of at least 9% per GB/T 2585-2007.
Q: Where is the 38kg rail commonly used? A: In mines, ports, industrial plants and secondary or branch railway lines.
Q: Is the 38kg rail suitable for high-speed lines? A: No. High-speed corridors require heavier sections such as 60 kg/m with stricter quality control.
